[Python-Dev] Analog of PEP 448 for dicts (unpacking in assignment with dict rhs) (original) (raw)

Mario Corchero mariocj89 at gmail.com
Sun Nov 12 09:56:23 EST 2017

Do you mean making getitems call itemgetter?

At the moment we can already do with itemgetter:

from operator import itemgetter a,b = itemgetter("a", "b")(d)

I tend to post this every time the topic comes up, but: it's highly unlikely we'll get syntax for this when we don't even have a builtin to extract multiple items from a mapping in a single operation.

You mean subitems as attrgetter does? That would be actually quite cool!

d = dict(a=dict(b=1), b=dict(c=2)) ab, ac = itemgetter("a.b", "b.c", separator=".")(d)

I've created an issue in case something like that is desired: https://bugs.python.org/issue32010 No real strong push for it, happy to just close it if it does not get interest.

That said I am not sure it solves Ben requests as he seamed to be targetting a way to bind the variable name with the dictionary keys implicitly.

On 12 November 2017 at 10:06, Nick Coghlan <ncoghlan at gmail.com> wrote:

On 11 November 2017 at 16:22, Jelle Zijlstra <jelle.zijlstra at gmail.com> wrote: > 2017-11-10 19:53 GMT-08:00 Ben Usman <bigobangux at gmail.com>: >> I was not able to find any PEPs that suggest this (search keywords: >> "PEP 445 dicts", "dictionary unpacking assignment", checked PEP-0), >> however, let me know if I am wrong. >> > It was discussed at great length on Python-ideas about a year ago. There is > a thread called "Unpacking a dict" from May 2016.

I tend to post this every time the topic comes up, but: it's highly unlikely we'll get syntax for this when we don't even have a builtin to extract multiple items from a mapping in a single operation. So if folks would like dict unpacking syntax, then a suitable place to start would be a proposal for a "getitems" builtin that allowed operations like: b, a = getitems(d, ("b", "a")) operator.itemgetter and operator.attrgetter may provide some inspiration for possible proposals. Cheers, Nick. -- Nick Coghlan | ncoghlan at gmail.com | Brisbane, Australia

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